The Digital Ocean Forum #4 will take place on November 27–28, 2025, in Brussels, Belgium. This annual flagship event gathers ocean scientists, modelers, data experts, researchers, innovators, and policymakers to review recent progress and explore new opportunities for the co-development of the European Digital Twin of the Ocean (EU DTO). Building on the success of previous forums and the recent showcase of the EU DTO platform at the UN Ocean Conference 2025, the event will hi